Inductive loops have been employed for years in traffic management systems to provide vehicle detection and are often used to monitor traffic flow. When properly installed and maintained, the inductive loops provide a high level of accuracy. However, they are prone to fail due to any of the following: cracks in the pavement, freeze and thaw cycles, roadway displacement, poor installation, construction on the roadside and/or the roadway. When any part of the inductive loop wiring is damaged or destroyed, detecting vehicles with the inductive loop becomes erratic or stops entirely.
Detection devices are needed to solve the reliability problems of inductive loops. These detection devices need to be reliable, long lasting and/or more immune to the problems of weather and aging of the roadways and the detection devices.